When comparing Curl.js vs JSPM, the Slant community recommends JSPM for most people. In the question“What are the best client-side JavaScript module loaders?”JSPM is ranked 4th while Curl.js is ranked 8th. The most important reason people chose JSPM is:

JSPM is registry agnostic, it can pull packages from npm and github and is built in such a way it can support more.